A quasi-experimental pre-post study design with intervention and reference groups was employed to compare service use and costs in the 18 months following the establishment of a new CBOC. Fifteen CBOCs from 11 VISNs were included in the analysis. For specific aim 1, the intervention group was defined as existing users in the catchment area of a new CBOC and the reference group was defined as matched existing users outside CBOC catchment areas. Multivariate statistical regression analyses were used to estimate the impact of residing within the CBOC catchment area on use and cost in the post-period, controlling for patient casemix and use/cost in the 18 month pre-period. For specific aim 2, the intervention group was defined as zip codes in the catchment area of a new CBOC and the reference group was defined as matched zip codes outside CBOC catchment areas. Average use and costs for all users, existing users and new users from intervention zip codes and reference zip codes were compared.